Apparatus for signalling system

ABSTRACT

Apparatus for a signalling system. The apparatus includes a plurality of remote control units each of which is arranged to store self-check timing data therein. This data has a value representing a predetermined period of time the expiration of which corresponds to a predetermined time of day differing from the times of day associated with at least some of the other remote control units. At or following this particular time of day, a self-check operation is initiated for communicating a self-check message, including identification number data identifying the remote control unit, to a centralized communications center. A computer at the communications center receives and processes self-check messages produced by the remote control units and operates in response to each message from a remote control unit to note the identification number data therein and, using this data, to derive self-check timing data for use by the remote control unit in the next self-check operation. The self-check timing data has a value representing a period of time the expiration of which corresponds to the same time of day at or following which the last self-check operation was initiated by the remote control unit. The new self-check timing data is communicated back to the remote control unit for use thereby in initiating the next self-check operation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application discloses subject matter which is disclosed, and claimed, in the following co-pending applications:

Ser. No. 965,808, filed Dec. 4, 1978, now U.S. Pat. No. 4,224,478, in the names of Robert J. Fahey and Martin L. Resnick, entitled "DATA TRANSMISSION CIRCUIT", and assigned to GTE Sylvania Incorporated and GTE Laboratories Incorporated;

Ser. No. 965,809, now U.S. Pat. No. 4,220,825, filed Dec. 4, 1978, in the name of Robert J. Fahey, entitled "TELEPHONE STATUS MONITOR CIRCUIT", and assigned to GTE Sylvania Incorporated;

Ser. No. 965,756, filed Dec. 4, 1978, now U.S. Pat. No. 4,224,602, in the names of Richard W. Anderson and Alfred I. Bottner, entitled "SIGNALLING DEVICE", and assigned to GTE Sylvania Incorporated;

Ser. No. 965,757, filed Dec. 4, 1978, now U.S. Pat. No. D-258,577, in the name of Alfred I. Bottner, entitled "Design for SIGNALLING DEVICE", and assigned to GTE Sylvania Incorporated;

Ser. No. 973,201, filed Dec. 26, 1978, now U.S. Pat. No. 4,220,87, in the name of Robert J. Fahey, entitled "D.C. POWER SUPPLY CIRCUIT", and assigned to GTE Sylvania Incorporated;

Ser. No. 973,218, filed Dec. 26, 1978, now U.S. Pat. No. 4,225,792, in the name of Robert J. Fahey, entitled "DETECTOR CIRCUIT", and assigned to GTE Sylvania Incorporated;

Ser. No. 25,298, filed Mar. 30, 1979, in the names of Richard W. Anderson and Alfred I. Bottner, entitled "Design for HOUSING FOR ELECTRONIC CIRCUITRY", and assigned to GTE Sylvania Incorporated;

Ser. No. 75,782, filed Sept. 17, 1979, now U.S. Pat. No. 4,255,669, in the name of Richard L. Naugle, entitled "SENSING APPARATUS", and assigned to GTE Laboratories Incorporated;

Ser. No. 75,769, filed Sept. 17, 1979, now U.S. Pat. No. 4,272,762, in the names of Richard L. Naugle and William L. Geller, entitled "EXIT-ENTRY APPARATUS", and assigned to GTE Laboratories Incorporated;

Ser. No. 094,015, filed concurrently herewith, now U.S. Pat. No. 4,281,394, in the names of Jeffery R. Fox, Arthur Margolies, Rob Moolenbeek and Martin L. Resnick, entitled "APPARATUS FOR MONITORING AND SIGNALLING SYSTEM", and assigned to GTE Laboratories Incorporated;

Ser. No. 094,018, filed concurrently herewith, now U.S. Pat. No. 4,286,331, in the names of Richard W. Anderson, J. Edward Schlener and Martin L. Resnick, entitled "APPARATUS FOR MONITORING AND SIGNALLING SYSTEM", and assigned to GTE Sylvania Incorporated and GTE Laboratories Incorporated;

Ser. No. 094,013, filed concurrently herewith, in the names of Richard W. Anderson and J. Edward Schlener, entitled "APPARATUS FOR MONITORING AND SIGNALLING SYSTEM", and assigned to GTE Sylvania Incorporated;

Ser. No. 094,012, filed concurrently herewith, in the names of Robert J. Fahey and Martin L. Resnick, entitled "TELEPHONE STATUS MONITOR APPARATUS", and assigned to GTE Sylvania Incorporated and GTE Laboratories Incorporated;

Ser. No. 094,014, filed concurrently herewith, now U.S. Pat. No. 4,273,960, in the names of Robert J. Fahey and Martin L. Resnick, entitled "APPARATUS FOR MONITORING USAGE OF A TELEPHONE", and assigned to GTE Sylvania Incorporated and GTE Laboratories Incorporated;

Ser. No. 094,245, filed concurrently herewith, now U.S. Pat. No. 4,295,208, in the names of Robert A. Norbedo and Martin L. Resnick, entitled "APPARATUS FOR SIGNALLING SYSTEM", and assigned to GTE Laboratories Incorporated;

Ser. No. 094,241, filed concurrently herewith, now U.S. Pat. No. 4,295,207, in the name of Martin L. Resnick, entitled "DATA PROCESSING APPARATUS FOR RECEIVING AND PROCESSING CODED WORDS", and assigned to GTE Laboratories Incorporated;

Ser. No. 094,016, filed concurrently herewith, now U.S. Pat. No. 4,284,849, in the names of Richard W. Anderson, Robert J. Fahey, William R. McClellan, and J. Edward Schlener, entitled "MONITORING AND SIGNALLING SYSTEM", and assigned to GTE Sylvania Incorporated;

Ser. No. 094,017, filed concurrently herewith, now U.S. Pat. No. 4,273,961, in the names of Hans G. Blank and Martin L. Resnick, entitled "APPARATUS FOR COMMUNICATING WITH PROCESSING APPARATUS OVER A TELEPHONE NETWORK", and assigned to GTE Laboratories Incorporated;

Ser. No. 094,243, filed concurrently herewith, in the names of Robert J. Fahey and Robert A. Norbedo, entitled "APPARATUS FOR SIGNALLING SYSTEM", and assigned to GTE Sylvania Incorporated and GTE Laboratories Incorporated;

Ser. No. 094,019, filed concurrently herewith, now U.s. Pat. No. 4,259,548, in the names of Robert J. Fahey, Robert A. Norbedo and J. Edward Schlener, entitled "APPARATUS FOR MONITORING AND SIGNALLING SYSTEM", and assigned to GTE Sylvania Incorporated and GTE Laboratories Incorporated;

Ser. No. 094,242, filed concurrently herewith, in the names of Robert J. Fahey and Martin L. Resnick, entitled "APPARATUS FOR MONITORING AND SIGNALLING SYSTEM", and assigned to GTE Sylvania Incorporated and GTE Laboratories Incorporated;

Ser. No. 094,246, filed concurrently herewith, now U.S. Pat. No. 4,301,515, in the names of Robert J. Fahey, Robert A. Norbedo and Martin L. Resnick, entitled "VARIABLE TIMING SYSTEM", and assigned to GTE Sylvania Incorporated and GTE Laboratories Incorporated.

The following co-pending applications are directed to apparatus which may be employed in the signalling and monitoring system of the present invention:

Ser. No. 75,783, filed Sept. 17, 1979, now U.S. Pat. No. 4,259,594, in the names of Jeffrey R. Fox, Arthur Margolies, and Rob Moolenbeek, entitled "ELECTRICAL POWER SUPPLY APPARATUS", and assigned to GTE Laboratories Incorporated; and

Ser. No. 084,976, filed Oct. 15, 1979, in the name of William L. Geller, entitled "DIGITAL COMMUNICATIONS RECEIVER", and assigned to GTE Laboratories Incorporated.

BACKGROUND OF THE INVENTION

The present invention relates to a monitoring and signalling system. More particularly, the present invention relates to a monitoring and signalling system such as a home health care system for monitoring the activities of individuals within their own homes, apartments, etc., and for providing bi-directional communication between these locations and a centralized communications center.

In recent years, as the general population has become older and the number of elderly persons in the population has increased, and also as a result of increased social welfare legislation directed to the needs of these persons, there has been an increased reliance and utilization of professional care institutions such as hospitals, nursing homes and retirement centers for providing health care and maintenance for these individuals. A large majority of these individuals are maintained and cared for in such institutions for good and proper reasons, most typically for the treatment of medical problems requiring medical facilities and equipment and the professional services of doctors, nurses and the like. However, there are a number of individuals who are presently maintained in institutions without medical reason. These individuals generally have no family or friends to care for them or who do not wish to impose upon or burden such family or friends and are prepared to sacrifice some measure of independence for the security and freedom from worry, anxiety, and loneliness that institutions can provide. It has therefore been recognized that if alternatives to institutionalization can be provided, especially for those individuals who do not require constant or continuing institutional attention or observation, while providing a substantial degree of security and independence for these individuals, preferably within their own homes, the burdens on the institutional care system can be reduced and result in lower health care costs. Any such alternatives which would also produce the same results for individuals other than the elderly, such as young handicapped, disabled or infirm adults, would also have the effect of improving the quality of life of such individuals and, at the same time, reducing health care costs.

A variety of apparatus and systems have been proposed heretofore directed to solutions to the problems as discussed hereinabove. One such system, developed in Sweden, is described in U.S. Pat. No. 3,885,235 and is adapted to monitor passively normal, routine activities of an individual in his or her own residence and to produce alarm conditions in the event these routine activities are not performed during some specified period of time, for example, a period of up to 24 hours. The system as described in the patent includes a plurality of actuating units which may be variously located in predetermined areas of the residence, such as halls, lavatories, bathrooms and bedrooms, and which may be associated with apparatus likely to be actuated or used routinely by the individual during the normal course of the day. This apparatus may include, by way of example, lighting circuits, radio sets, television sets and household appliances. Actuation or use of any one of the actuating units during the aforesaid specific time period will cause an electromechanical timer set to this time period to be reset and to repeat its timing cycle. In the event no actuating unit is actuated or used during the time period, for example, due to inactivity or incapacity of the individual, the timer times out after the time period and an alarm condition, for example, in the form of an audible or visual alarm, is produced by the system indicative of this situation. If the alarm condition was produced as the result of inactivity rather than incapacity, the user may disable the system by the use of a master switch. The master switch may also be used to disable the system when the individual leaves his or her residence for a prolonged period of time, for example, for a period of time greater than the time period of the timer. Upon return of the individual, the system is arranged so that routine operation of any one of the actuating units will have the effect of resetting the timer and causing the timer to repeat its timing cycle. The system as described above may also include an alarm switch in the residence for use by the individual in producing alarm conditions during emergencies, such as medical emergencies or accidents.

In a later version of the system as described in the aforementioned U.S. Pat. No. 3,885,235, known as the "Automatic Warning Aid (AWA)", additional features are provided, including a direction sensitive photocell optics arrangement in the bathroom; an electronic timer having two time periods, specifically, a short time period associated with the bathroom optics arrangement and a longer time period associated with all other actuating units; a pre-alarm cycle effective prior to an actual alarm cycle and during which an alarm condition can be cancelled or aborted; and remote alarm transmission. In this later system, recognition is given to the fact that the majority of accidents occur in the bathroom. Accordingly, the system is arranged so that when an individual enters the bathroom the direction sensitive photocell arrangement detects this entry and causes the timing cycle of the electronic timer to be reduced to its short time period, for example, about one hour. If the individual does not exit within the one hour period, for example, due to incapacity or inactivity of the individual, a pre-alarm cycle will be initiated and, if the pre-alarm cycle is not terminated or aborted by the individual, an actual alarm cycle will be initiated after passage of a short period of time (e.g., about 1/2 hour). In the event the individual exits from the bathroom within the one hour period, the direction sensitive photocell arrangement will detect this exit and cause the timing cycle of the electronic timer to be set or returned to its longer time cycle, for example, about 8 hours. During any pre-alarm cycle caused by non-use of any of the actuating units within the individual's residence the individual may, unless incapacitated, abort or cancel the pre-alarm cycle by actuation or use of any actuating unit (which resets the timer) so that no actual alarm condition will be produced. The alarm condition may be generated locally or, if desired, transmitted over a telephone network, for example, in the form of a recorded message, to a central alarm center from which communication with the individual may be attempted and/or help sent or summoned.

Another system which has been proposed heretofore for passively monitoring the activities of individuals within their own residences and for producing appropriate alarm conditions is described in U.S. Pat. No. 3,989,900. In this system, the use of a standard telephone is monitored. Each time the handset of the telephone is lifted off or removed from the cradle of the telephone, for example, during the making and receiving of routine telephone calls, a timer set to cycle through a predetermined time period, for example, up to 24 hours, is caused to be reset and to repeat its timing cycle. So long as the telephone is used during the time period of the timer no alarm condition will be produced. If no use of the telephone is made during the time period of the timer, for example, due to incapacity or inactivity of the individual, a local alarm condition is produced and, simultaneously therewith, a magnetic tape player is actuated to dial continuously a plurality of telephone numbers of locations at which help may be available and to transmit a prerecorded message that help is needed at the address of the individual. If the timing out of the timer was due to inactivity rather than incapacity, the user may, in response to the local alarm condition, abort the alarm condition and data transmission sequence (within a time period of about 90 seconds) by simply lifting and replacing the handset back on the cradle of the telephone thereby resetting the timer. This latter operation may also be used to reset the timer at such time as the individual plans to leave his residence for a period of time less than the predetermined time period of the timer. An activating switch is also provided in the system for activation of the alarm condition in the case of emergencies. The abovementioned patent also contemplates the use of a high speed digital dialer and transmitter in place of the aforementioned magnetic tape player. In this case, the timing out of the timer will produce a local alarm condition and, unless the alarm sequence is aborted (for example, within a 5 minute period), the digital dialer and transmitter will operate to seize a telephone line to establish communication with the central station. The dialing of the central station continues until a receiving signal has been received from the central station whereupon an identification signal can be sent to the central station.

In still other systems which have been proposed heretofore for enabling individuals to be maintained within their own residences while providing appropriate alarm signalling in emergency or accident situations, a transmitter is employed by an individual to communicate under a variety of conditions with control apparatus located on the premises. The transmitter, which may be in the form of a small, portable hand held unit or a unit carried in a pocket or purse or attached to clothing or worn as a pendant (e.g., see U.S. Pat. Nos. 4,121,160 and 4,134,108), may be used by the individual to communicate with the control apparatus in a variety of situations, including emergency or accident situations, to respond to periodic check signals or stimuli from the control apparatus as an indication that "all is well" (e.g., see U.S Pat. No. 3,662,111), or to respond within predetermined time periods of timer apparatus. The signals from the transmitter are typically coded rf signals employed to control circuitry within the control apparatus. Activation of a transmitter in an emergency or accident situation, or failure to activate a transmitter at required times, for example, due to incapacity or inactivity, will ordinarily cause an alarm cycle to be initiated which, if not aborted or cancelled by the individual, will cause an alarm sequence to be initiated for informing others of the emergency, accident or inactivity situation. The alarm sequence may be variously initiated by digital or tape dialers and include one or more messages, identification data, etc., to be communicated, for example, over a telephone network, to such organizations or individuals as an emergency center, the police or fire department, ambulance service, doctors, paramedics, rescue teams, relatives, friends or neighbors. In many systems, repeated attempts will be made to communicate alarm information to a central location using one or more telephone numbers, and some systems may include handshaking operations between a local control unit and central equipment and include test calls for determining proper functioning of the systems.

While the various systems as described above are useful to a degree in alleviating the problems of individuals living alone, they all have serious shortcomings and disadvantages which limit their effectiveness and usefulness. As a group, for example, these systems utilize simple data handling, processing and communication techniques, being limited more or less to tape and digital dialing, the transmission and reception of limited amounts of data, and, in some cases, simple handshaking and parity-checking operations. It is not known, for example, that any of these systems employ computers, microprocessors or the like capable of performing significant and substantial data processing, either within the residences of individuals or at central locations. As a result, these systems are susceptible to a high false alarm rate and reliability problems, these latter problems being especially exascerbated in those systems employing mechanical tape dialers and electromechanical timers and the like. In these systems, therefore, due to the lack of sophisticated data processing and communications, there is inadequate guarantee, if any, that a successful and satisfactory transmission of data, such as alarm conditions or information, has been achieved so that those persons charged with acting on this information can adequately discharge their duties. The systems as described above, perhaps also as a result of their limited data processing and communications capabilities, have limited capability in detecting or pinpointing, and distinguishing between, the malfunction of various critical components thereof, for example, actuating units, control apparatus or telephone lines. In these systems, the malfunction of a critical component thereof will, assuming that such malfunction is somehow communicated to a responsible person (e.g., as a result of an alarm condition), ordinarily require service personnel to enter a person's home and check out the entire system or a major part thereof to pinpoint the particular source of trouble or malfunction. Further, in those systems employing timers having one or more resettable time periods (e.g., a one-hour bathroom cycle and/or a regular 8-hour cycle), these time periods are alterable only within the residences of individuals, thereby requiring costly service calls by service personnel to effect the alterations. The alteration of timer periods only within the residences of individuals can also have the effect of increasing the chances of tampering by these individuals.

In addition to the abovementioned general shortcomings and disadvantages, the systems as described hereinabove have other and more specific shortcomings and disadvantages which limit their effectiveness and usefulness in a home health care environment. For example, in the Swedish systems the multiple actuating units and the alarm switches are hard-wired to the control units. This hard-wiring operation makes the installations of these systems complex, time-consuming and expensive. In addition, while using several diverse "passive" actuating units, the Swedish systems do not make use of a common passive actuating unit generally available and used frequently in most residences, namely, the telephone. While the systems described in U.S. Pat. No. 3,989,900 employ a telephone as a passive actuating unit, no other passive actuating units are employed, thereby reducing the scope of monitoring of the activities of individuals. In addition, only on/hook to off/hook transitions of the telephone are used to reset the timer in the control unit. Thus, at the conclusion of a telephone conversation the off/hook to on/hook transition resulting from the individual replacing the handset on the cradle of the telephone will not reset the timer, thereby having the probable effect of increasing the alarm rate of the system. In the case of the systems employing rf transmitters for transmitting alarm conditions or responding to predetermined check signals, these systems similarly do not employ passive actuating units and thereby have a reduced scope of monitoring of the activities of individuals and, therefore, a reduced effectiveness.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention, apparatus is provided for a signalling system such as a home health care system as described hereinabove. The apparatus in accordance with the invention includes a plurality of remote control means. Each of the remote control means includes a self-check timing means operative to store self-check timing data therein, and means operative to alter the self-check timing data stored in the self-check timing means so as to have a predetermined value at the expiration of a predetermined period of time. The expiration of the predetermined period of time corresponds to a time of day differing from the times of day associated with at least some of the other remote control means. A self-check message generating means operates at or following the self-check data in the self-check timing means having the predetermined value to initiate a self-check operation and to produce a self-check message indicative of the self-check operation.

A processing means is arranged to receive and process messages produced by the plurality of remote control means. The processing means operates in response to each message from a remote control means to derive self-check timing data for use by the remote control means in the next self-check operation. The self-check timing data in this instance represents a period of time the expiration of which corresponds to the same time of day at or following which the last self-check operation was initiated by the remote control means. The self-check timing data is included in a message produced by the processing means and received by receiving means provided in the remote control means. The receiving means operates in response to the message to cause the self-check timing data in the message to be applied to and stored in the self-check timing means for use thereby in initiating the next self-check operation.

BRIEF DESCRIPTION OF THE DRAWING

Various objects, features and advantages of a monitoring and signalling system in accordance with the present invention will be had from a detailed discussion taken in conjunction with the accompanying drawing in which:

FIG. 1 is a schematic block diagram of a monitoring and signalling system in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described in detail in co-pending patent application Ser. No. 094,019, now U.S. Pat. No. 4,259,548, filed Nov. 14, 1979 in the names of Robert J. Fahey, J. Edward Schlener and Robert A. Norbedo. The following portions of the aforementioned patent are incorporated herein by reference:

(a) FIGS. 2-66 and the corresponding brief description thereof under the heading "BRIEF DESCRIPTION OF THE DRAWING"; and

(b) The entire portion of the specification following the heading "DETAILED DESCRIPTION OF THE INVENTION". 

What is claimed is:
 1. In a signalling system, apparatus comprising:a plurality of remote control means each comprising:self-check timing means operative to store self-check timing data therein, said self-check timing data representing a predetermined period of time the expiration of which corresponds to a predetermined time of day, said self-check timing data having a value whereby the expiration of the predetermined period of time corresponds to a time of day differing from the expiration times of day of at least some of the other remote control means; clocking operative to alter the self-check timing data stored in the self-check timing means so as to have a predetermined value at the expiration of the predetermined period of time; and self-check message generating means operative at or after the self-check data in the self-check timing means having the predetermined value to initiate a self-check operation and to produce a self-check message indicative of the self-check operation; and processing means arranged to receive and process messages produced by the plurality of remote control means, said processing means being operative in response to each message from a remote control means to derive self-check timing data for use by the remote control means in the next self-check operation, said self-check timing data representing a period of time and having a value whereby the expiration of the period of time corresponds to the same time of day at or following which the last self-check operation was initiated by the remote control means, said processing means being operative to produce a message containing the self-check timing data; and said remote control means further including means operative to receive the message produced by the processing means and in response thereto to cause the self-check timing data in the message to be applied to and stored in the self-check timing means for use thereby in initiating the next self-check operation.
 2. Apparatus in accordance with claim 1 wherein:each of the plurality of remote control means has an identification number assigned thereto differing from the identification numbers of at least some of the other remote control means; the self-check message generating means of each remote control means operates at or after the self-check timing data in the self-check timing means having the predetermined value to initiate a self-check operation and to produce a self-check message containing identification number data identifying the remote control means; and the processing means operates in response to the self-check message to detect the identification number data in the message and, using this data, to derive the self-check timing data for use by the remote control means in initiating the next self-check operation and to produce a message containing the self-check timing data.
 3. Apparatus in accordance with claim 2 wherein:the plurality of remote control means and the processing means are interconnected by a transmission medium for allowing the bidirectional communication of messages between the remote control means and the processing means.
 4. Apparatus in accordance with claim 3 wherein:the transmission medium interconnecting the plurality of remote control means and the processing means is a telephone network.
 5. Apparatus in accordance with claim 3 wherein:the self-check timing data stored in each self-check timing means represents a count expressed in fractions of an hour; and the clocking means operative to alter the self-check timing data includes means operative to decrement the count represented by the self-check timing data once for each fraction of the hour.
 6. In a signalling system, apparatus comprising:a plurality of remote control means each having an identification number assigned thereto differing from the identification numbers of at least some of the other remote control means, each of the remote control means comprising:self-check timing means for storing self-check timing data therein; clocking means operative to alter the self-check timing data stored in the self-check timing means so as to have a predetermined value at the expiration of a predetermined period of time, said expiration initially corresponding to a time of day directly related to the identification number of the remote control means; and self-check message generating means operative at or after the self-check data in the self-check timing means having the predetermined value to initiate a self-check operation and to produce a self-check message indicative of the self-check operation; and processing means arranged to receive and process messages produced by the plurality of remote control means, said processing means being operative in response to each message from a remote control means to derive self-check timing data for use by the remote control means in the next self-check operation, said self-check timing data representing a period of time the expiration of which corresponds to a predetermined time of day associated with the remote control means and differing from the expirating times of day of at least some of the other remote control means, said processing means being operative to generate a message containing the self-check timing data; and said remote control means further including means operative to receive the message produced by the processing means and in response thereto to cause the self-check timing data in the message to be applied to and stored in the self-check timing means for use thereby in initiating the next self-check operation.
 7. Apparatus in accordance with claim 6 wherein:the self-check message generating means operates at or after the self-check timing data in the self-check timing means having the predetermined value to initiate a self-check operation and to generate a self-check message containing identification number data identifying the remote control means; and the processing means operates in response to the self-check message to detect the identification number data in the message and, using this data, to derive the self-check timing data for use by the remote control means in initiating the next self-check operation and to generate a message containing the self-check timing data.
 8. Apparatus in accordance with claim 7 wherein each remote control means comprises:memory means arranged to store self-check timing data therein having a value directly related to the particular identification number assigned to the remote control means; and means operative to access the memory means and to extract and apply the self-check timing data stored in the memory means to the self-check timing means.
 9. Apparatus in accordance with claim 8 wherein:the plurality of remote control means and the processing means are interconnected by a transmission medium for allowing the bi-directional communication of messages between the remote control means and the processing means.
 10. Apparatus in accordance with claim 9 wherein:the transmission medium interconnecting the plurality of remote control means and the processing means is a telephone network.
 11. In a signalling system, apparatus comprising:a plurality of remote control means each having an identification number assigned thereto differing from the identification numbers of at least some of the other remote control means, each of the remote control means comprising:self-check timing means for storing self-check timing data therein, said self-check timing means being initially operative to store self-check timing data therein having a value directly related to the identification number of the associated remote control means, said self-check timing data representing a predetermined period of time; clocking means operative to alter the self-check timing data initially stored in the self-check timing means so as to have a predetermined value at the expiration of the predetermined period of time; and self-check message generating means operative at or after the self-check data in the self-check timing means having the predetermined value to initiate a self-check operation and to produce a self-check message indicative of the self-check operation; and processing means arranged to receive and process messages produced by the plurality of remote control means, said processing means being operative in response to each message from a remote control means to derive self-check timing data for use by the remote control means in the next self-check operation, said self-check timing data representing a period of time and having a value whereby the expiration of the period of time corresponds to a predetermined time of day associated with the remote control means and differing from the expiration times of day of at least some of the other remote control means, said processing means being operative to generate a message containing the self-check timing data; and said remote control means further including means operative to receive the message produced by the processing means and in response thereto to cause the self-check timing data in the message to be applied to and stored in the self-check timing means for use thereby in initiating the next self-check operation.
 12. Apparatus in accordance with claim 11 wherein:the self-check message generating means operates at or after the self-check timing data in the self-check timing means having the predetermined value to initiate a self-check operation and to produce a self-check message containing identification number data identifying the remote control means; and the processing means operates in response to the self-check message to detect the identification number data in the message and, using this data, to derive the self-check timing data for use by the remote control means in initiating the next self-check operation and to produce a message containing the self-check timing data.
 13. Apparatus in accordance with claim 12 wherein each remote control means comprises:memory means arranged to store self-check timing data therein having a value directly related to the particular identification number assigned to the remote control means; and means operative to access the memory means and to extract and apply the self-check timing data stored in the memory means to the self-check timing means.
 14. Apparatus in accordance with claim 13 wherein:the plurality of remote control means and the processing means are interconnected by a transmission medium for allowing the bi-directional communication of messages between the remote control means and the processing means.
 15. Apparatus in accordance with claim 14 wherein:the transmission medium interconnecting the plurality of remote control means and the processing means is a telephone network.
 16. Apparatus in accordance with claim 15 wherein:the self-check timing data initially stored in each self-check timing means is a count having a value equal to the identification number of the associated remote control means and the self-check timing data subsequently stored in each self-check timing means represents a count expressed in minutes; and the means operative to alter the self-check timing data includes means operative to decrement the count represented by the timing data at a rate of once per minute. 